RECORD: Darwin, C. R. Ascension. [Beagle field notes] [7.1836] CUL-DAR40.93-96 Transcribed by Kees Rookmaaker (Darwin Online, http://darwin-online.org.uk/)
REVISION HISTORY: Transcribed from the microfilm by Kees Rookmaaker, corrections and editing against the manuscript by John van Wyhe 7.2010, further corrections against the manuscript by Gordon Chancellor 10.2010. RN4
NOTE: This document is written in pencil, except where otherwise noted, on heavy greyish cream-coloured paper which is watermarked "SLADE 1834"; the writing is in places very faint and smudged and hence many words are illegible. Compare with Darwin's account of his visit to Ascension in Journal of researches, pp. 585-589.
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Reproduced with permission of the Syndics of Cambridge University Library and William Huxley Darwin.
very red Hill
Cross Hill; Lower part a white feldspathic Lava, in plates, on surface, not very cellular. — great irregular stream of blank lava — nature unknown — very slightly amygdoidal edge of stream 35-40 ft thick. — great valleys with numerous layer of all sizes sorted pumice pebbles. Volcanic ashes — fragment — sandstone, leaves some ridge of the older compact white rocks, & the blank cellular common Kinds uncovered — action of wind.
these layers slope up to great central mass, yet doubtful whether they belong to that series. — Between 20-30 Craters, slope to SE, perhaps the greater nucleus; action of trade wind & greater degradation on that side [sketch] shore Southside case having affected.
Mem sandstone outside hardened, perhaps explaining Coquimbo if amygdoidal, magnesium, limestone — no structure of shells. — pink color. — —
Green Hill, sharp point of small breccia of slightly decomposed scoriae, (base seen on return cellular grey lava) surrounded by quaquaversal dip high angle of sandstone scoriae fragments — large fragment of compact grey lava, surrounded by flat composed 100-200 ft deep of horizontal strata of dike many brown & blank sandstone like Galapagos Cuidado; covered by thick mass of coarse angular fragments — these fine beds are brecciated white like Chiloe. — Wherever super[illeg] by stone [sketch]: — Great Hollow [oval] flat bottom. wells perpendicular prismatic structure, quite compact at base, but higher up mingled with scoriae. — dip no sort of [rule] — yet not horizontal. — Enlargement of gorge, stopped
dip, at mouth, would have been dug like 200 ft hard rock —another 200 the horizontal strata — look as if whole land subsided, but not so for matter descends in curved slope, on valley head of hollow —
filled up; originally much deeper: — matter of top thins on slopes [sketch].
Precipitated from air although large fragments. ? Pumice on NW side do?? —
White Hill &
other Holy Head appear to form a sort of mass or circle,
in that part of Isld & to appear in other parts; surrounds
Green Hill on N, NW & NE. — cannot say whether one great or many craters.
— capped with rubbish. — No different rocks of hollow forms basal parts of
also a white Trachytic rock with brown specks; But these hills are mainly formed of white, from tufa, with occass. crystals of glassy felspar. & few smaller fragments of scoriae — it is in places laminated; is traversed by sort of plates, frequently assuming a sphaerical form (containing inside the softer matter), which plates is compact hard & resembles a Lava; external appearance of these plates, like some very hard rocks. Its association (manner of) with the white Trachytes I do not understand. — This rock has been subject to great faults, & some soft alternating lands. Such I believe belong to this age, with sedimentary dike — & inclined to nearly vertical towards Crater. —
Obsidian seated in band in hillocks at foot of great mountain,
or Garden House — strata perhaps dip inwards structure not understood. — wide
open faults — To the Westward [termination] shut up by stream of
black lava (P) — to the Eastward dips under ground — Obsidian generally jet
black, sometimes green. — Is capped by substance, which appear like an irregular
carious, siliceous slate —
but looks in parts just like petrified
wood, — laminated laminae slightly convoluted mostly vertical, — however unlike
this may be to a melted rock contains bands of small angular (peas to bullets)
balls of obsidian first thought pebbles, but afterwards found thin layers
of long extent thus placed. — Obsidian appears in this rock at junctions,
in large irregular [balls] or masses. — This rock is intimately [mingled] associated with other varieties, of compact, evenly laminated grey hard rocks
(& other convoluted) with brown rocks (D). [unknown symbol or sketch] (a).
— variety E occurred above this petrified wood substance, is closely connected
but may possibly form passage to next kinds. — This slate is only few yards
thick, is capped by soft white stone, then alternation of black white (B).
laminated vertically & soon convoluted in parts. — although specimens
grey — mass looked white is certainly allied to rock (N). These masses far
thicker than the obsidian — alternations may be obscurely seen. — NB. Obsidian
passes into Pumice variety — What strange varieties altogether associated
— Rock (B) internally resembling white varieties near the white Trachyte of
first day —
Riding School. Hill — very curious — consists of white mass like that of White Hill, of which (N) is specimen with brown obscure crystals. — this is associated with a dark blackish green rock (O) of same structure, sometimes masses at other times connected by the green, forming a rounded breccia blending with the white — contains angular & small fragments of black scoriae, & one or two semi rounded pebbles of more compact rocks — a few scattered grand angular masses, of many tuns weight of a purplish
trachyte (vesicular cavities bronzed mesotype) aspect aqueous
deposition. These must have been pitched out of a Volcano. — with white matter
whole surface thickly strewed with brown (general aspect of Hill; white
like base of Garden Hill). oddly curved plates, these brittle hard, most sonorous
like Clinkers of Galapagos. — These plates vary,
as specimens show, from very thin to about inch thickness, constitution similar
of all — frequently crystals of glassy feldspar — plates lie in all planes
— commonly affect curvilinear form on grand scale — branch off in all irregular
directions resist decomposition, hence Parasols. — [sketch]
& superficial coating. Plates project upwards some feet & several
yards in length. — when struck noise of big drum & highly elastic
like iron plate not visible in hand specimen — appear like volcanic rock,
no dikes form like veins of segregation. Occur in green equally on white kinds.
— There is also in white rock honeycombed masses less hard sonorous [often]
More yellow &c reddish pieces like the spherico-honeycombed sandstone
sometimes associated with Volcanic rocks (L). — join on to other plates but
rather different. — Plates in vast numbers — Hill not high — surmounted by
circular depression filled up with same shaped strata &c — no crateriform
strata, but from fragment & shape cannot doubt is old Crater, 3/4 miles
in diameter. — in greater part of crest & nearing whole base the white
rocks can be traced. — The north side part is formed by Lavas. — In the white
fault, on one side, there occur vertical, slightly sinuous, irregular veins,
or rather veins for it thins out & [dips] & again
reappears of red sandstone looking stuff, containing thinner veins, more than
one or two, of white, or pink Jasper strikes fire — passes in agate apparently.
— appear like veins of segregation —
A few yards further there occurs
in dark greenish rock which near is stained reddish. — This rock indeed in
parts has tendency to become red & jaspery — further on. [Patches] I could not make out connection of white or very pale. do. Jasper slightly carious (G). — On se where lava occur there is large [hummocky] hill, with irregular flattish top, may be old crater attached to border but scarcely appears so — of cellular grey & compact Lavas (some like those at base of Hollow); associated with volcanic rock in streams, & connection with white Crater not distinct. — These on face of crater, contain large patches of regular yellow Jasper — & in some more fine bright red. — Here Lava compact stony finely slaty, with few cysts of Feldspar. — associated with some reddish finely cellular. scoriaceous Lava in igneous brecciated state; these contain veins angular patches & cavities with mamillated surface of do. — The yellow occurs too plentifully I should think to be posterior formation. — There is other [hummock] near Border. —
Concave strata near margin dip to 20-30° in centre horizontal outside part white friable bits of pumice. — brown more decomposed small fragment; white. — These finer grained decomposed finer volcanic ashes yellow. upper parts pink, rather more compact; whitish do — about 8 ft in centre, of black glossy minute scoriae. — white slopes [sketch] at very small angle to South. from white external ring have upper parts removed, origin: some other crater [sketch] (a) (a) drainage from hardness. — Effect most singular. — in the yellowish light mass decomposed ashes. — numerous balls of various sizes, concentric layers, sometimes united laterally — very nearly cylindrical. Trough — chiefly in one particular stratum, a few above — As matter not subaqueous ? aerial formation? if concentric layers differ probably so — curious — Volcanic [hail].
m mon] ink nib tests.
At base of Garden Hill, tough conglomerates are found nature doubtful, specimen (T), curious Brown & red Trachyte (latter rare). Hornstone Porphyry — Dr Webster small peak. Some of the dark Lava assume singular fluted & twisted forms. I saw but few. —
on the two
From descent in crust: < >/ thick diameter of frond? — margin sinuous, crenated, like Serpentine.
?purely calcareous? contain particles of shells. — glossy [illeg] encrust lilke Olivine
compact & scoriaceous rock & pieces of shells within wash of violent surf. on windward & leeward side of rock — colour varies. black — to grey. — what is cause of colour? — is said soon to reappear if removed. — beach in front purely calcareous — in interstices formation may be seen to commence in aggregated particles, thaws like ice on Limestone rocks. — then redeposition which perhaps taking place
from upon these [ridge]
[sketch] from the frond like surface. — These
[frondescent] forms bear some relation of arborescent like
coral salt of Copiapo waterfall, which tree in mountain, does
to that same in forest. — This [glaze] same as what cement
At certain times of every year coating white compact calcareous matter on tidal rocks, but chiefly on this one side of Isd
Great Gypsum stalactites on roof of caverns near sea, is Selanite // Effect of sea, but little smooth Lava, bring in no proof of River. —
Beaches broad & high of which calc sand. in much, no organic
structure; tides remove parts & then in lower part this rock is found.
— the less hard kinds will form in year generally quite pure,
in some parts with volcanic impure, [imbedded] pieces of
Corallaria, shells & turtle egg, of course anything used in freestone
& Limestone. — contains occasional pebbles of volcanic rocks —
in few parts cement stained from brown with do — Generally cement glistening,
coats each particles; & then central parts become removed. Mem. Coquimbo?
examine specimens — some laminated kinds, very hard, V. specimen. — At St Helena
drift by winds harmonizes with absence of shells — Red particles have shells
in coral. Harder when exported. —
[sketch] shifting sand
pink — peculiar colour only examined to one bodies.
St. Helena Paper shells, winnowed, only difference with Ascension.—
Mem. Galapagos Volc. sand. although Trachyte there modern, generally before basalts, under higher pressure.
Trade wind] added ink.
St. Helena Paper shells, winnowed, only difference with Ascension.—] added ink.
In one great modern stream on SW and innumerable beds whole surface whitish. Great cavities become filled up with these layers like wood yellowish-[brown] irregular masses
on fracture pungent smell — [surely] smell like Cocos Isd.=
line of coast matter. — like guano? neighbouring volcanic rock. coated [illeg] broken incrust frondescent, ? I believe result
also of dung? — V Specimen. —
Green hill in the [black] [scoriae] many fragments of white
Syenite. Porph. of Andes — also a Bluish layer crystal rock. — In another
spot said to be soil ridge; two kinds of hard granitic rocks — I believe altered.—
Trachyte & Syenite
Great modern streams, — not really modern consists of black
cellular Trachyte with few cysts ( — N.B. The [cellular]
parts have at least as many cysts as compact)
irregular (Specimen) conical hummock, at distance like [Juncalillo] 200 ft high
[4 words illeg] 20 - 30 yards where decomposed [illeg] has
permanent — [only] structure kind of [illeg]
consolidation, has carved ten lines in motion of stream, but no overlapping [sketch?] compact angular fragment of scoriae [illeg] = ribs sometimes leave these composed of angular concretionary lumps — these streams appear of rather posterior origin. — Lava darkens — having
singular effect. — A stream more modern than there [NW] end. near Guano — wonderfully rough — margin almost wall more than 30 ft high — surface fractured hillock. Wonderful— lava, little fluidity, see specimen. —
A SW Volcano. Quantities of Bombs. size of double fist, to mans chest,[illeg]size boys head. external encrusted. — some irregular shapes [sketch] a elongated central reddish or black [high] by cellular, mixed irregularly with compact portions — a concretion structure — no case [glassy] — alone told story (forms)—
[sketch] A. finely cellular. (B) layer compact, (C) very cellular.
This structure, although not very common, occurred too often to be
accidental (see specimen). — easily frangible sometimes layers. not flattened on part P. — yet now lying in part on hard layer
must have been bed of ashes; wind removed — hence wind may
cause & rain in valleys of the ashes. great deposits. —
Add to St Helena paper, certain fact of great cliffs, caused by degredation.
Ascension] ink, written over other entries.
this page is dirty as if it was the outermost of the folded packet.
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